The heart of a computer is a magnetic disk drive which typically includes a rotating magnetic disk, a slider that has read and write heads, a suspension arm above the rotating disk and an actuator arm that swings the suspension arm to place the read and/or write heads over selected circular tracks on the rotating disk. The suspension arm biases the slider into contact with the surface of the disk when the disk is not rotating but, when the disk rotates, air is swirled by the rotating disk adjacent an air bearing surface (ABS) of the slider causing the slider to ride on an air bearing a slight distance from the surface of the rotating disk. When the slider rides on the air bearing, the write and read heads are employed for writing magnetic impressions to and reading magnetic signal fields from the rotating disk. The read and write heads are connected to processing circuitry that operates according to a computer program to implement the writing and reading functions.
In typical systems, a main pole of a magnetic head senses information stored on the magnetic disk. In some instances, a damascene process may be used to produce the main pole in the magnetic head. The damascene main pole process requires the formation of a trench by dry etch, e.g., reactive ion etching (RIE), into a dielectric material, e.g., alumina, silicon dioxide, etc., followed by deposition of a dielectric side gap and a conductive seed layer that are both incorporated into the side gap. In order to include a wrap around shield structure in the magnetic head, the dielectric material which is all around the now-filled trench is removed. Alumina can be wet etched easily and isotropically, but when the trench comprises of silicon dioxide, a dry etch containing fluorine compounds is traditionally used, but this etch is not very isotropic and some residual silicon dioxide may be left behind near the bottom of the main pole, especially in the corner formed where the structure meets the underlying etch stop layer. This residual material changes the head geometry and therefore adversely impacts the performance of the magnetic head.
Therefore, there is a need in the art of magnetic head production for a way to remove the silicon dioxide matrix surrounding the newly-formed magnetic pole by wet etch without etching away the side gap. Some attempts have been made to provide this solution, such as using a solution having HF (hydrofluoric acid), but these solutions also etch the main pole material, such as when the main pole comprises a CoNiFe alloy. Therefore, a solution which can remove the silicon dioxide matrix without etching the main pole and side gap material would be very beneficial to the art.